Engine



Patented Nov. 8, |898.

wv. E. PRALL.

E N s l N E.

(Application filed Nov. 22, 1895.)

(No Model.)

Nrrnn STATES.

PATENT OFFICE.

WILLIAM EDGAR PRALL, OF VASHINGTON, DISTRICT OF COLUMBIA, AS- SIGNOR TO THE STORAGE POWER COMPANY, OF VEST VIRGINIA.

ENGINE.

SPECIFICATION forming part of Letters Patent No. 613,939, dated November 8, 1898.

Application led November 22, 1895l Serial No. 569,755. (No model.)

To all whom it may concern.-

Be it known that LWILLIAM En GAR PRALL, a resident of Washington, in the District of Columbia, have invented `certain new and useful Improvements in Apparatus for Converting Heat into Power; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it pertains to make and use the same.

The improvement relates to converting heat into power, and has for its object to make improvements in apparatus therefor, and more particularly in means for introducing and utilizing hot water in the cylinder or cylinders in manner to increase the effective pressure; and the invention consists in the construction hereinafter described and particularly pointed out.

In the accompanying drawings, Figure l is a plan, partly in section, of an apparatus suitable for practicing the improvement. Fig. 2 is an enlarged section of a detail, and Fig. 3 is a section on line 3 3 of Fig. 2.

Referring to Fig. l, numeral 1 indicates a tank adapted to hold superheated water under a high pressure.

Numerals 2, 3, 4, and 5 denote the cylinders of a compound engine. Superheated water under high pressure is admitted from. the tank to cylinder 2 and passed from it in the form of water and vapor or steam through cylinders 2, 3, 4, and 5 in series to vdrive the several pistons by quadruple expansion. A part of the invention, however, is independent of multiplied expansion, being applicable to a single cylinder.

6 indicates pistons, and 7 vpiston-rods.

S denotes a pipe leading from the bottom of the water-tank to cylinder 2.

9 denotes valve-chests, and 10 slide-valves of usual form.

11 indicates valve-rods, 12 the operatingeccentrics, and 13 a crank-shaft.

14 are connecting-rods.

16 denotes exhaust-conduits whereby the Valve-chests of the several cylinders 2, 3, 4, and 5 communicate each with the valve-chest of the succeeding cylinder, and 17 denotes a final exhaust.

Water heated to about 400 Fahrenheit can be admitted to cylinder 2 through valvechests 9 and exhausted from it through the sliding valve with water heated ,toanything approaching the temperature named soon destroys the usefulness of the valve, and it also involves an unnecessary Waste of the hot waterthat is, of` power. c

It has been found necessary to lprovide means for introducing hot water into cylinders in small and measured quantities to avoid the waste; but heretofore no means has been provided for obviating the destructive or wearing eect of Very high heat and pressure upon the valves. To overcome this difiiculty, I provide pop-valves situated in the path of the piston and adapted to be opened by it very near the end of its stroke. 1S indicates such valves, and 18 guides for their stems. (See Fig. 3.) 19 is a pipe conveying water from the tank to the valve-chamber 20 through a branch or branches 2l. The valve-chamber 2O being in free communication with the Water-space of the tank, the valvesk 18 are normally held closed bypressure from the tank and opened by the piston at the close of its forward stroke. As it is important that but a small quantity lof water be admitted at each stroke, the tappet-valve extends but a small distance through the cylinder-wall and the valve is not opened until the piston has nearly reached the end of the cylinder. The valve is moved slightly and is open but an instant, the proper effect being produced by a momentary contact with the piston.- At such time the piston-rod, the

pitman, and the crank should be at or nearly approaching the dead-center and not far enough behind to effect a reversal of the engine.

As a very small amount ofy water suffices for working the engine, an instantaneous opening and closing of the valve is required, and such an effect cannot be secured when valve-gear is interposed with the effect t0 consume time in its movement and hold the valve open longer than by the instantaneous action of the piston upon a puppet-valve,

IOO

as herein represented and described. Such speedy and brief opening of the valve is characteristic of the invention, and the direct contact of the piston with a puppet-valve is the most simple and convenient means of effecting it known to me, though others are not excluded, provided they instantaneously open and close the valve with substantially the same effect. By use of the puppet or pop valve wear and cutting, such as are incidental to slide-valves, are avoided.

Obviously the engine cannot be started by the sole use of pop-valves constructed and arranged as set forth. The slide-valve 10 of cylinder 2 can be operated to admit Water for this purpose,or other means may be employed. The highly-heated medium admitted to cylinders will tend to maintain initial heat. Said valve and similar valves for controlling the utilization of exhaust in the several cylinders in case of multiple expansion can be used temporarily for ascending steep grades or other purposes requiring an exceptional amount of power, and a cock or valve 22, controlled in any usual way, as by a rod 23, can be provided.

24 denotes a steam-pipe continuous with pipe 19, whereby the steam-space of tank 1 may communicate with each valve box or chamber 2O of cylinders 3, 4, and 5. 26 is a cock or valve back of its connection with pipe 27 to close said pipe 24. 27 is a pipe whereby the lower or water space of tank l may communicate with the steam-pipe 24, and 28 is a valve or cock to close such pipe. By suitable manipulation of these valves either hot Water or steam or both may be admitted to the valveboxes and immediately to the cylinders. The several cylinders may be protected from loss by radiation in any usual manner. No special provision for maintaining the heat of the hotwater cylinder 2 is required on account of its small size and the very high heat of water supplied to the entire engine through it.

The amount of steam or water admitted to a cylinder can be regulated by the length of the valve-stem or the manipulation of the main exhaust-valve or by throttling the supply-pipe.

Referring to the drawings, it will be understood that the pistons are represented near the end of the path and that the exhaust-port is in communication with the space about the valve to be opened. The continuance of the pistons travel will open the valve as described and simultaneously the eccentrics will close the said exhaust and open an exhaust-port at the opposite end of the cylinder.

Having described my invention, what l claim is- 1. In an engine the combination of a holder for superheated water under pressure, an e11- gine-cylinder, a charging-conduit whereby the holder and cylinder may communicate, a piston for the cylinder, a valve, means for momentarily opening said valve to admit water to reverse the piston, said valve being closed by pressure from the superheated watercharging conduit immediately upon the reversal of the piston, and exhausting devices, substantially as described.

2. In a compound engine, the combination of a holder for superheated Water under pressure, a charging-conduit, engine-cylinders having valves and valve-casings inclosing chambers in free communication with the holder and in communication with the cylinders when the valves are open, exhausting devices comprising conduits whereby the cylinders communicate to exhaust from one to another and nally from the engine, and pistous for said cylinders, the valves being situated in the path of a moving part of the engine and adapted to admit sufficient water to drive the engine by instantaneous contact at suitable intervals with said moving part, said valves being closed by pressure from the holder immediately upon the reversal of the pistons, substantially as described.

3. In a compound engine, the combination of a holder for su perheated Water under pressure, engine cylinders having valves and valve-casings inclosing chambers in free communication with the holder and in communication with the cylinders when the valves are open, conduits whereby the cylinders communicate to exhaust from one to another and finally from the engine, pistons for said cylinders, the valves being situated in the path of the moving part of the engine and adapted to admit sufficient superheated water to drive the engine by instantaneous contact at suitable intervals with said part and closed by pressure from the holder immediately upon the reversal of the pistons, and supplementary devices for starting the engine, substantially as described.

4. In a compound engine, the combination of a holder for superheated water under pressure, engine cylinders having valves and valve-casings inclosing chambers in free communication with the holder and in communication with the cylinders when the valves are open, the valves being adapted to be closed by pressure from the holder immediately upon the reversal of the pistons, conduits whereby the cylinders communicate to exhaust from one to another and finally from the engine, pistons for said cylinders, said valves being situated in the path of the moving part of the engine and adapted to admit sufficient superheated water to drive the engine by instantaneous contact at suitable intervals with said part, and supplementary devices for starting the engine, said devices comprising a distinct valve and separate superheated water-supply pipe, substantially as described.

In testimony whereof I have signed this speciiication in the presence of two subscribing witnesses.

WILLIAM EDGAR PRALL.

Witnesses:

GEORGE SroLL, O'rro MARKUsKE.

IOO

IIO 

